1. Field of the Invention
The invention relates to a thin film magnetic head having at least an inductive magnetic transducer for writing, and a method of manufacturing the same.
2. Description of the Related Art
Recently, an improvement in performance of a thin film magnetic head has been sought in accordance with an increase in a surface recording density of a hard disk drive. A composite thin film magnetic head, which has a stacking structure comprising a recording head having an inductive magnetic transducer for writing and a reproducing head having a magnetoresistive (hereinafter referred to as MR) element for reading, is widely used as the thin film magnetic head.
An improvement in performance of the recording head is also sought in accordance with an improvement in performance of the reproducing head. Factors that determine the performance of the recording head include a throat height (TH). The throat height refers to a length of a pole portion between an air bearing surface that is a recording head surface facing a magnetic recording medium (hereinafter referred to as xe2x80x9ca recording mediumxe2x80x9d) and an edge of an insulating layer for electrically isolating a thin film coil for generating a magnetic flux. Optimization of the throat height is desired for the improvement in the performance of the recording head. The throat height is controlled by the amount of polishing of the air bearing surface.
To increase the surface recording density of the performance of the recording head, it is necessary to finely narrow a write width (a write track width) on the recording medium during recording and thus increase a write track density. For this purpose, it is necessary to realize a recording head having a narrow track structure in which a width (a pole width) of the pole portion of the recording head on the air bearing surface is as narrow as a few microns to the submicron order. Semiconductor fabrication technology enabling high-accuracy microfabrication is widely used as means for realizing the above-mentioned narrow track structure of the pole portion. Currently, various efforts are being made in order to enable ultrafine fabrication of the submicron order.
However, the achievement of high-density recording requires the solution of other factors, even if the ultrafine fabrication of the pole portion is made possible and also the accuracy in fabricating the pole portion is improved.
Factors inhibiting high-density recording include, for example, the occurrence of side erase, the deterioration in overwrite characteristics, and so on. Herein, the xe2x80x9cside erasexe2x80x9d refers to a phenomenon in which a write operation for writing information on a specified write track causes information to be written on an adjacent region as well as the specified write track region and thus magnetic data already recorded on the adjacent region is magnetically overwritten with the written information and is lost. The xe2x80x9coverwrite characteristicsxe2x80x9d refer to magnetic overwrite characteristics: magnetic data on a recording medium is updated by overwriting existing magnetic data with new magnetic data. Both the occurrence of side erase and the deterioration in overwrite characteristics cause considerable deterioration in recording characteristics of a thin film magnetic head. More particularly, a tendency to cause these problems is more noticeable as a write track is narrower and smaller. Because of these facts, rapid improvement to the above-mentioned problems is needed with the increase in a write track density due to the narrowing and reduction of the pole width of the thin film magnetic head.
The invention is designed to overcome the foregoing problems. It is an object of the invention to provide a thin film magnetic head which can obtain good recording characteristics even when a pole width is narrowed and reduced, and a method of manufacturing the same.
There is provided a thin film magnetic head of the invention including: two magnetic layers magnetically coupled to each other and having two magnetic poles which face each other with a gap layer in between near and in a recording-medium-facing surface to be faced with a recording medium, a thin film coil provided between the two magnetic layers, and an insulating layer for insulating the thin film coil from at least one of the two magnetic layers having a first magnetic layer portion and a second magnetic layer portion, the first magnetic layer portion having a uniform-width portion extending away from a recording-medium-facing surface facing a recording medium and defining a write track width on the recording medium, and the second magnetic layer portion coating a region in which the thin film coil portion is provided and partly overlapping and magnetically coupled to a part of the first magnetic layer portion, wherein a distance LD (xcexcm) between a position of an edge of the second magnetic layer portion closest to the recording-medium-facing surface and a position of the recording-medium-facing surface and a thickness LT (xcexcm) of a portion of the first magnetic layer portion exposed to the recording-medium-facing surface satisfy LDxe2x89xa7LTxe2x88x922.0 (xcexcm).
In the thin film magnetic head of the invention, the write track width on the recording medium is defined by the uniform-width portion of the first magnetic layer portion. The second magnetic layer portion is arranged so as to partly overlap a part of the first magnetic layer portion, and thus the second magnetic layer portion is magnetically coupled to the part of the first magnetic layer portion.
There is provided a method of manufacturing a thin film magnetic head of the invention including: two magnetic layers magnetically coupled to each other and having two magnetic poles which face each other with a gap layer in between near and in a recording-medium-facing surface to be faced with a recording medium, a thin film coil provided between the two magnetic layers, and an insulating layer for insulating the thin film coil from at least one of the two magnetic layers having a first magnetic layer portion and a second magnetic layer portion, the first magnetic layer portion having a uniform-width portion extending away from a recording-medium-facing surface facing a recording medium and defining a write track width on the recording medium, and the second magnetic layer portion coating a region in which the thin film coil portion is provided and partly overlapping and magnetically coupled to a part of the first magnetic layer portion, wherein the first magnetic layer portion and the second magnetic layer portion are formed so that a distance LD (xcexcm) between a position of an edge of the second magnetic layer portion closest to the recording-medium-facing surface and a position of the recording-medium-facing surface and a thickness LT (xcexcm) of a portion of the first magnetic layer portion exposed to the recording-medium-facing surface satisfy LDxe2x89xa7LTxe2x88x922.0 (xcexcm).
In the thin film magnetic head and the method of manufacturing the same of the invention, it is preferable that a minimum value LTmin of the thickness LT satisfy LTmin=xe2x88x920.5Bs+1.5, and a maximum value LDmax of the distance LD satisfy LDmax=0.5Bs+3.0, where Bs is a saturation magnetic flux density.
In the thin film magnetic head and the method of manufacturing the same of the invention, the one magnetic layer may be made of a material containing a nickel-iron alloy, or the one magnetic layer may be made of a material containing iron nitride. In the former case, it is preferable that the distance LD be within a range of 0xe2x89xa6LD less than 3.5 (xcexcm) and the thickness LT be within a range of 1.0 (xcexcm) less than LTxe2x89xa63.5 (xcexcm). In the latter ease, it is preferable that the distance LD be within a range of 0xe2x89xa6LD less than 4.0 (xcexcm) and the thickness LT be within a range of 0.5 (xcexcm) less than LTxe2x89xa63.5 (xcexcm). In the former case, it is more preferable that the thickness LT be within a range of 1.0 (xcexcm) less than LT less than 3.5 (xcexcm). In the latter case, it is more preferable that the thickness LT be within a range of 0.5 (xcexcm) less than LT less than 3.5 (xcexcm).
Other and further objects, features and advantages of the invention will appear more fully from the following description.